Researchers from Brigham Young University analyzed the way in which clinical depression can blur and mess with memory, and found that the worse symptoms get, the harder it is for patients to distinguish and recall their experiences.
"That's really the novel aspect of this study - that we are looking at a very specific aspect of memory," Brock Kirwan, a psychology and neuroscience professor at BYU, said in a press release.
Depression has long been linked to poor memory, and to test why this might be, Kirwan and his former grad student, D.J. Shelton, had participants go through a computer-aided memory test in which they viewed objects on a screen and reported as to whether or not they had seen it before (old object) or not (new object), or seen something similar.
As for both old and new objects, participants diagnosed with depression did fine on the tests and were able to accurately recall objects that they had seen or not seen, but when it came to spotting objects that were similar to but not the same as ones they had seen before, they often got it wrong, most commonly reported that they had seen it before as an old object.
"They don't have amnesia," Kirwan explained. "They are just missing the details."
The ability to recall details is known as "pattern separation," the researchers inspired by a game to practice this skill on the popular children's television show, "Seasme Street."
When people suffer from depression, recalling specifics may become more difficult, whether it comes to finding lost car keys or trying to remember which family members you've told something very personal to. Looking more closely about how depression effects the brain, Kirwan explained, may help scientists understand this phenomeon.
"There are two areas in your brain where you grow new brain cells," he said. "One is the hippocampus, which is involved in memory. It turns out that this growth is decreased in cases of depression."
Depressed people may also experience short-term memory less, according to Discovery Fit & Health, one of the side effects of the mood disorder. Chemical imbalances in the brain that cause depression may also impact signals and "messages" sent back and forth, thus disrupting the flow of memory and the ability to concentrate.
